import java.util.*;

class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int X = Integer.parseInt(sc.next());
		int Y = Integer.parseInt(sc.next());
		int L = Integer.parseInt(sc.next());

		int ans = (Math.abs(X)+L-1)/L + (Math.abs(Y)+L-1)/L;

		if(Y>=0){
			if(X!=0){
				ans++;
					}
		}
		else{
			ans = ans + 2;
			if(X!=0){
				ans++;
			}
		}
				
		System.out.println(ans);
	}
}